Figure 1

In vitro sequential selection of invasive populations from MCF-7 cells using Matrigel Invasion Chambers. (A and B) In each cycle, cells invading the Matrigel were fixed with 10% formalin-neutralized buffer and stained with crystal violet on the underside of the chamber (A), and then the numbers of invading cells were counted under a microscope (B). Data are the means ± SD (n = 3). Statistical analysis was performed by Student's t test. *, P < 0.01, compared with MCF-7 cells. (C) Images of morphology of MCF-7 and MCF-7-14 cells in culture. MCF-7-14 cells were propagated as non-adherent spheres (arrow). (D) Proliferative rates of MCF-7 and MCF-7-14 cells. (E) Western blotting analysis for the expression of HER-2 and ER-α in MCF-7 and MCF-7-14 cells.